On 20 Nov 2011, at 17:27, Jason Resch wrote:

Hi Bruno, I had few questions regarding some of the things said in your post.On Sat, Nov 19, 2011 at 3:49 AM, Bruno Marchal <marc...@ulb.ac.be>wrote:On 19 Nov 2011, at 03:02, Pierz wrote: David Deutsch's idea of a good explanation is one that closely matches the structure of the thing it describes, allowing for little variation. The vast variation in the possible worlds where UDA could be invoked makes it a bad explanation, in those terms.You have just not (yet) understood the role of the 1/3 person povdistinction in the reasoning. UDA shows that physics is determinedby a relative measure on computations. If this leads to predict thatelectron weight one ton then mechanism is disproved. UDA shows thatphysics is entirely reduce to computer science/number theory in avery specific and unique way (modulo a variation on the arithmeticaldefinition of knowledge).Couldn't the UD predict various computational histories anddifferent types laws of physics for different observers?

`I don't think so, because physics is given by ALL computations going`

`through your state, and that means any state accessible by a universal`

`numbers/machines. The "different observers" and "other universes" have`

`to be too much different. They cannot be Turing universal. If they`

`are, you appear in their computations, and so become part of your`

`physics.`

`I will reexplain this to Stephen and Johnathan, so don't worry if this`

`is not clear.`

Of course the electron weighing a ton might be ruled out fromobservation if such electrons are incompatible with life, but Idon't see that the UD could ever perfectly derive the laws ofphysics if there are multiple computational histories compatiblewith observers.

`By UDA, physics is neither a computation, nor the result of a`

`computation. It is the result of interference of all (relative)`

`computations. The computation leading to non universal observers have`

`a measure null with respect to the "real (arithmetical) measure". They`

`exist in UD*, but does not influence what we observe. They are "white`

`rabbit computations".`

For example, might there be such histories that have observers butno electrons at all? I see the UD perhaps being used in the futureto derive a rough estimate of the probabilities for different commonuniverses observers might expect to find themselves in, but nothingdefinite.

`This is not entirely excluded, but then the mass or the existence of`

`electron is a geographical phenomenon.`

This is not a problem for an Everett -type multiverse, in which the universes are bound together by consistent physical laws which allow one to speak of a proportion of universes in which event x occurs. However, in a mathematical platonia where all possible calculations occur, and nothing outside of them, there can be no such ordering principle.If the Everett idea works, and is the solution, (which has not yetbeen completely proved) then the UDA conclusion is that the Everettsimultion in the UD wins the "measure battle", and we HAVE tojustify this from computer science alone.More general physical principals like the Schrodinger equation mightbe applicable to all observers if it is truly, as Russell staid, atheory of observation. But something like the weight of theelectron, the Gravitational constant are, in my mind, more properlyconsidered local properties rather than global principals.

`This is possible. It would make the mass of the electron similar to`

`the mass of the planet around the sun, that is: a geographical`

`contingent reality, as unpredictable than being myself in W or in M`

`after a self-duplication. The advantage of comp is that it gives what`

`is really invariant for all universal numbers, in any lawful and`

`persistent (from its point of view) environments.`

More on this later. Bruno http://iridia.ulb.ac.be/~marchal/ -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.